ELT-2, A 2ND GATA FACTOR FROM THE NEMATODE CAENORHABDITIS-ELEGANS

We have previously shown that a tandem pair of (A/T)GATA(A/G) sequence s in the promoter region of the Caenorhabditis elegans gut esterase ge ne (ges-1) controls the tissue specificity of ges-1 expression in vivo . The ges-1 GATA region was used as a probe to screen a C. elegans cDN A expression library, and a gene for a new C. elegans GATA-factor (nam ed elt-2) was isolated. The longest open reading frame in the elt-2 cD NA codes for a protein of M(r) 47,000 with a single zinc finger domain , similar (approximately 75% amino acid identity) to the C-terminal fi ngers of all other two-fingered GATA factors isolated to date. A simil ar degree of relatedness is found with the single-finger DNA binding d omains of GATA factors identified in invertebrates. An upstream region in the ELT 8 protein with the sequence C-X(2)-C-X(16)-C-X(2)-C has so me of the characteristics of a zinc finger domain but is highly diverg ed from the zinc finger domains of other GATA factors. The elt-2 gene is expressed as an SL1 trans-spliced message, which can be detected at all stages of development except oocytes; however, elt-2 message leve ls are 5-10-fold higher in embryos than in other stages. The genomic c lone for elt-2 has been characterized and mapped near the center of th e C. elegans X chromosome. ELT-2 protein, produced by in. vitro transc ription-translation, binds to ges-1 GATA-containing oligonucleotides s imilar to a factor previously identified in C. elegans embryo extracts , both as assayed by electrophoretic migration and by competition with wild type and mutant oligonucleotides. However, there is as yet no di rect evidence that elt-2 does or does not control ges-1.